


Past Mistakes

by camichats



Series: Imagine James and Sirius Prompts [121]
Category: Harry Potter - J. K. Rowling
Genre: Angst, Everybody Lives, Getting Together, M/M, Misunderstandings, One Night Stands, Slytherin Sirius Black
Language: English
Status: Completed
Published: 2020-01-26
Updated: 2020-01-26
Packaged: 2021-02-27 15:54:18
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,907
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22419571
Author URL: https://archiveofourown.org/users/camichats/pseuds/camichats
Summary: Back at Hogwarts, Sirius and James exchanged furtive kisses, but it never went anywhere. The last thing Sirius expects is for James to bring it up again, ten years later.
Relationships: Sirius Black/James Potter
Series: Imagine James and Sirius Prompts [121]
Series URL: https://archiveofourown.org/series/752925
Comments: 12
Kudos: 165





	Past Mistakes

**Author's Note:**

> For the prompt: “Hi I just want to say that i love your blog and could you like do something where james is a single parent and sirius is harry's teacher and sirius is a slytherin.Thats all i got for a prompt but i hope you can do it.Once again love your blog ,its awesome and your writing is great.😍”

Sirius watched Harry Potter walk in his classroom, and his first thought was _Everyone thinks he looks like his father?_ There was some resemblance, sure, but everyone he'd heard talk about them made it sound like Harry was a clone of James. Not er that Sirius was really on a first name basis with father or son. Back in the day, he and one James Potter had had an ill advised love affair that ended when James realised Lily was more in the future he wanted and Sirius realised that James couldn't fix him. That they'd been on opposite sides of the school hadn't helped matters any-- even if they'd been on the same side for the war. Sirius saw Harry Potter walk in, and he thought he looked more like Lily Evans. But maybe that was just because he didn't want to admit that James had moved on where he hadn't ( ~~that one night didn't count for anything, it had been a mistake, James had said as much even before they were done, he'd been balls deep in Sirius and instead of saying how great he felt or something, he said in a guilty, broken voice that he should be better than this~~ ). 

Sirius was a professor to an entirely new class of witches and wizards, and he should be focusing on that instead of the kid of someone he'd fooled around with over a decade ago. Besides, Harry was in Gryffindor, and House dynamics never really left-- he thought that was hippogriff shite, but maybe that was because he'd spent a good several minutes arguing with the Hat that he had to be in Slytherin. 

* * *

Harry was bloody _hilarious_. The way he talked to Snape with no fear even though the fucking bat was scowling down like he wanted to kill him? Perfect. 

And despite the animosity or apathy Sirius had been expecting from Harry, it kinda seemed like he was one of the kid's favourite professors. He wondered if James knew about that, and then he got pissed at himself for caring enough to think about James's opinion and thoughts about him (if there were any to begin with). 

Harry was... well not a 'good kid' in that he paid perfect attention in his classes and did all his homework to exacting standards, but he was nice and paid enough mind to what was going on around him that he wasn't hopeless. Considering how Sirius (and Harry's own father) had been at that age, he was doing bloody well magnificent. 

All of this to say that Sirius was getting too invested. He was teaching the kids of plenty of people he'd gone to Hogwarts with, and he wasn't paying this much attention to any of the rest of them. 

* * *

"I'm... sorry?" Sirius said, looking between the three kids and hoping that they were about to crack up with a joke well done. 

"Professor Snape is trying to steal the Sorcerer's Stone!" Harry said again, and the earnestness in his voice certainly _sounded_ real. 

"Er." Merlin fuck, how was he supposed to respond to this? Dumbledore did not cover this in Teaching 101. "He's a right tosser, I'll admit that, but he's not so stupid as to try and steal the Stone." Sirius lifted a foot to keep walking, then stopped, frowning. "Wait, how do you lot know about the Stone?" 

All three of their eyes went wide, and they exchanged guilty looks. 

Damn it. 

* * *

When Sirius saw James Potter for the first time in ten years, James was cracking up laughing beside his son's hospital bed. "Careful there Potter, you'll hurt yourself being so distraught." 

Instead of turning somber or ignoring him entirely, James's attention turned to him and he brightened. "Sirius!" 

Shit, they were doing the first name thing. 

~~_Stay, Sirius had said. Don't go yet, stay a couple minutes more, what can it hurt?_ ~~

~~_James had run a thumb over Sirius's bottom lip, staring at him with equal amounts of longing and self loathing. Goodbye, Black._~~

"Hey. Proud of your son, the troublemaker?" 

"Like you're one to talk," James snorted. 

"Not judging, just making an observation. Where's Lily?" 

"She and Marlene are celebrating their anniversary, I didn't want to interrupt her since it's not an emergency. I sent her a letter," he added, glancing at Harry, "so she might show up anyways, I dunno." 

"She probably won't," Harry said for Sirius's benefit. "I'm fine, I don't know why they made you come here." 

"No one made me sprog, they mentioned you were hurt and I showed up." 

"I just wanted to check in," Sirius said with a smile at Harry. "But now that I see you're okay, I'm gonna go." He gave James a nod goodbye, then turned on his heel and left. 

"Sirius, wait up!" James called after a few seconds. By that point, Sirius was already in the corridor, so he paused, half turning back to see him. James made sure the door of the Hospital Wing was closed before he faced Sirius full on. "Hey, erm." His voice was low, attitude more serious than it had been before. "I wanted to say I'm sorry. For how I treated you last time we saw each other." 

"It's fine," Sirius said, an automatic smile on his face. 

"No it's not, and I know you don't think it is, either." 

That took the wind out of Sirius's sails, and he dropped the expression with a sigh. "I don't know what you expect me to say. You made a mistake, it happens." They all made mistakes, but Sirius made more than the average person. He made so many that they were all tangled and interwoven until he didn't know where one ended and another began. There was that one getting-to-know-you question, about how if you could fix one mistake what would it be, and Sirius never knew what answer he should give because they were all related to each other. But maybe, in this case, the mistake had been thinking that he could ever be anything other than a temporary option for James. 

"Yeah except when you say that, I'm not sure you know which part I'm talking about." 

Sirius glanced down the empty corridor, then at the closed door. "This isn't really the place for this." 

"I agree. Let me buy you dinner?" 

"I don't really think that's a good idea," Sirius said, shifting uncomfortably. If they went to dinner and it felt like a date, Sirius was going to make a complete arse of himself. All he'd ever wanted was for James to want him too. A few years apart hadn't changed that, and even now, with James showing him the barest hints of interest, he wanted to grab him and- Merlin, not even kiss him, just hold him. 

"Right, well, I mean," James said, the words flopping out in quick succession nonsensically. "Maybe not. But I'd like to try anyways." 

"Good for you. Not gonna happen." 

James blinked, taken aback. He wasn't used to Sirius saying no to him, even if it had been years and years since they'd talked. 

"You apologised, I accepted, that's all this needs to be. Tell Harry I hope he heals up soon, yeah?" Sirius said, then walked away. 

He thought that would be the end of it. 

He should have known better. 

* * *

Someone knocked on the door to Sirius's flat, and he frowned, looking towards it in complete confusion. He barely lived here because he stayed at Hogwarts during the school year, and it's not like he had friends beyond Regulus, who always used the floo. A stray muggle neighbour, perhaps? No need to make them wait when he could just walk over and tell them to leave. 

Except he opened the door and came face to face with James. "What are you doing here?" 

"You said no to dinner." 

Sirius leaned against the door frame as he kept one hand on the knob, effectively blocking James from entering. "Yes, except I meant no to talking about it, not just to dinner." 

"I think you should-" James started to say, then he made himself stop talking. Swallowed thickly. "Right. That er, makes sense." He didn't leave, and Sirius didn't close the door. "I ruined it. If I hadn't come to you the night Lily and I split, you might let me in right now. We might... have half a chance. That's my fault and I-" James shook his head. "I'm sorry." 

"You split?" Sirius asked. 

"What? Of course we split, Lily and I haven't been together in ages, I thought everyone knew that." 

"No, I meant, that night." Sirius breathed in and out, looking at James like he was truly seeing him for the first time in the past few days. "I thought you were- going back to her. You know? We'd had some fun, and you were-" Sirius stopped, throat clicking. "It sounds kinda stupid when I say it now." 

"Not stupid. Makes a little more sense actually. I was thinking you thought you were a rebound or summat, but that I was cheating with you, that's er, much worse." 

Sirius ran an aggravated hand through his hair, then reached out, fisted it in James's shirt, and yanked him inside. "Why are you so bloody difficult all the time?" he muttered before pressing forward in a desperate kiss. 

James met him force for force, and they were pushing and clawing at each other in a way that wasn't completely pleasant but neither of them cared because they had _missed_ each other. 

"Don't go," Sirius whispered, then didn't give James a chance to answer, kissing him again. "Please," he said, the word mushed against his mouth because he hadn't pulled away. 

"'m not going anywhere, I promise." 

* * *

James stayed, but Sirius alternated between latching onto him like a grindylow and giving him space like he was worried James couldn't move if he needed to. When the latter happened, James would roll closer or pull him back in. 

He traced a finger across the lines of Sirius's ribs. It made Sirius shiver, but he never asked James to stop so he didn't. "I'm sorry," he said quietly. 

"You've said that." 

"I've been half in love with you since we were thirteen, and this whole thing has been..." he trailed off with a sigh. 

"Not ideal?" Sirius offered, and James snorted. 

"Thank you for putting it so delicately." He kissed Sirius's shoulder then, just because he could. "Still. I hate that it happened the way it did." 

"Yeah but do me a favour and stop bringing it up. I only want to think about where we go from here, not the shite we've been through." 

"If it'll make you happy," James agreed with a small shrug. 

"Thanks." He pulled James in for a slow kiss, then gave a rueful smile. "I know I asked you to stay, but you do have a kid to get back to. You should probably go." 

"Nope. Harry's over at the Weasley's." 

Sirius raised an eyebrow. "Hoping you'd get shagged?" 

"That was the best case scenario." 

"What was the worst case?" Sirius asked, not really expecting an answer. 

"Spending all night crying into my tea." 

"Aw poor baby," Sirius mocked. 

James laughed. "That's the shot of it, yeah. But it means I get to stay with you all night, no interruptions." 

"Won't say no to that." 

"That's what I was hoping." 

**Author's Note:**

> This is from a prompt driven blog @[imaginejamesandsirius](https://imaginejamesandsirius.tumblr.com) on tumblr. Feel free to drop by!


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